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Re: st: RE: RE: RE: RE: Excluding Observations


From   "Raphael Fraser" <raphael.fraser@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: RE: RE: RE: Excluding Observations
Date   Mon, 15 May 2006 17:28:29 -0500

Many thanks. It worked!
Observations before transfusion will be kept in the data set. When
Sickle Cell Disease patients are transfused it "interferes" with their
"normal" (or what clinicians call steady state) haematology. Hence the
data are being excluded.


On 5/15/06, J.Fischer@lse.ac.uk <J.Fischer@lse.ac.uk> wrote:
I meant the accumulated time after visit with treatment.
He does not have that yet. The  he will also have obs with dov == 1 and
90 days after treatment

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: 15 May 2006 23:04
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: RE: RE: Excluding Observations

No. He already has that. You must use
the data on transfusions.

Nick
n.j.cox@durham.ac.uk

J.Fischer@lse.ac.uk

> It looks like to me he has to construct a time variable that
> accumulates the number of days since last visit

Nick Cox

> A visit results in a transfusion whenever t is 1.
>
> gen ttime = dov if t == 1
>
> This results in missings whenever t is 0.
> Hence we fill in missings following the usual cascade principle
> documented at http://www.stata.com/support/faqs/data/missing.html
>
> bysort id (dov): replace ttime = ttime[_n-1] if mi(ttime)
>
> Here I am assuming that you want each patient treated separately.
>
> Then the time since the last transfusion is simply
>
> gen sincettime = dov - ttime
>
> Then you can exclude whatever you want. You have to work out what to
> do with observations before the first transfusion (on record).
>
> -etime- is superfluous here.
>
> Nick
> n.j.cox@durham.ac.uk
>
> Raphael Fraser
>
> > I would like to exclude from my data set all observations up to 90
> > days AFTER a transfusion (i.e. t = 1). The variable etime
> is the  time
>
> > elapse since last visit. Can any one help?
> >
> >          id         dov   t   etime
> >      57   26apr1977   0      57
> >      57   27apr1977   0       1
> >      57   28jun1977   0      62
> >      57   27jul1977   0      29
> >      57   19aug1977   1      23
> >      57   12sep1977   0      24
> >      57   27sep1977   0      15
> >      57   30nov1977   0      64
> >      57   28feb1978   0      90
> >      57   22jan1990   0      55
> >      57   23jan1990   0       1
> >      57   22jun1990   0     150
> >      57   01aug1990   0      40
> >      57   06aug1990   0       5
> >      57   12sep1990   1      37
> >      57   19sep1990   0       7
> >      57   21sep1990   0       2
> >      57   28sep1990   0       7
> >      57   14nov1990   0      47
> >      57   28nov1990   0      14
> >      57   21jan1991   0      54
> >      57   29apr1991   0      98
> >      57   23aug1991   0     116
> >      57   29aug1991   0       6
> >      57   20sep1991   0      22
> >      57   30sep1991   0      10
> >      57   28nov1991   0      59
> >      57   20jan1992   0      53
> >      57   21jan2002   0      35
> >       57   27may2002   0     126
> >      57   31may2002   0       4
> >      57   07jun2002   0       7
> >      57   09jul2002   0      32
> >      57   09oct2002   0      92
> >      63   28dec1974   0       0
> >      63   29dec1974   0       1
> >      63   08jan1975   0      10
> >      63   15may1975   0     127
> >      63   30jun1975   0      46
> >      63   29dec1975   0     182
> >      63   12jan1976   0      14
> >      63   19jan1976   0       7
> >      63   30mar1976   0      71
> >      63   28jun1976   0      90
> >      63   22oct1976   0     116
> >      63   25oct1976   0       3
> >      63   24nov1976   1      30
> >      63   04dec1976   0      10
> >      63   06dec1976   0       2
> >      63   21dec1976   0      15
> >      63   21jan1977   0      31
> >      63   26jan1977   0       5
> >      63   18feb1977   0      23
> >      63   28mar1977   0      38
> >      63   31may1977   0      64
> >      63   13jun1977   0      13
> >      63   28jun1977   0      15
> >      63   31aug1977   0      64
> >      63   03sep1977   0       3
> >      63   06sep1977   0       3
> >      63   27sep1977   0      21
> >      63   07oct1977   0      10
> >      63   05nov1977   0      29
> >      63   08nov1977   0       3
> >      63   27nov1977   0      19
> >      63   07dec1977   0      10
> >      63   16dec1977   0       9
> >      63   18dec1977   0       2
> >      63   19dec1977   0       1
> >      63   10jan1978   0      22
> >      63   11jan1978   0       1
> >      63   12jan1978   0       1
> >      63   14feb1978   1      33
> >      63   22feb1978   0       8
> >      63   28feb1978   0       6
> >      63   17mar1978   0      17
> >      63   04apr1978   0      18
> >      63   07jun1978   0      64
> >      63   26jun1978   0      19
> >      63   14jul1978   0      18
> >      63   21jul1978   0       7
> >      63   09aug1978   0      19
> >      63   14aug1978   0       5
> >      63   11sep1978   0      28
> >      63   24sep1979   0      17
> >      63   27sep1979   0       3
> >      63   29sep1979   1       2
> >      63   14dec1979   0      76
> >      63   07jan1980   0      24
> >      63   21sep1982   0      46
> >      63   04oct1982   0      13
> >      63   17dec1982   0      74
> >      63   22dec1982   0       5
> >      63   25dec1982   0       3
> >      63   01jan1983   0       7
> >      63   04jan1983   0       3
> >      63   24jan1983   0      20
> >      63   15mar1983   0      50
> >      63   28jun1983   0     105
> >      63   28sep1983   0      92
> >      63   04oct1983   0       6
> >      63   09jan1984   0      97
> >      63   30jan1984   0      21
> >      63   28mar1984   0      58
> >      63   28jun1984   0      92
> >      63   01oct1984   0      95
> >      63   16oct1984   0      15
> >      63   20dec1984   0      65
> >      63   24dec1984   0       4
> >      63   03jan1985   0      10
> >      63   08jan1985   0       5
> >      63   27mar1985   0      78
> >      63   30apr1985   0      34
> >      63   01may1985   1       1
> >      63   13may1985   0      12
> >      63   14may1985   0       1
> >      63   11jun1985   0      28
> >      63   02jul1985   0      21
> >      63   19aug1985   0      48
> >      63   23sep1985   0      35
> >      63   01oct1985   0       8
> >      63   18oct1985   0      17
> >      63   24oct1985   0       6
> >      63   03dec1985   0      40
>
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